Carbon Sequestration 

It is the process of capturing and storing atmospheric carbon dioxide. It is one method of reducing the amount of carbon dioxide in the atmosphere with the goal of reducing global climate change.

Types of Carbon Sequestration

• Biological carbon sequestration: It is natural storage of carbon dioxide. This includes storage in plants (naturally done through photosynthesis) trees, soil, and ocean carbon sequestration. The roots of plants and trees are excellent at carbon sequestration, storing vast amounts of carbon in there as well as in the leafy growth we see. 
• Geological carbon sequestration: It is when CO2 is injected into porous geological rock formations. This type of carbon sequestration is currently being implemented in industrial production. Industries, such as steel, energy, and natural gas production, send carbon dioxide runoff deep into the earth, trapping it, so it doesn’t spill into the atmosphere.
• Technological carbon sequestration: It is an attempt to create a useful byproduct from excess carbon dioxide. 
  • One group of scientists is perfecting a method that changes CO2 into methane and water. Methane can then be used as fuel for electricity or to power vehicles. 
  • Scientists have explored the possibility of creating a raw material from CO2 and have created a substance called graphene. Graphene’s use is still limited, but you can already find it in devices such as your smartphone’s screen. 
  • Other technological carbon sequestration methods are still in a nascent stage. Processes such as direct air capture can capture CO2 emissions in the atmosphere but is currently an uneconomical choice to use on a larger scale.

Carbon Sink 

• Carbon sinks are places and/or products that sequester and store carbon as organic or inorganic compounds for different periods of time. Essentially, anything that absorbs more carbon than it emits into the atmosphere through natural or artificial processes can be considered a carbon sink.
• In the pre-industrial era, carbon emitted into the atmosphere was usually balanced – on a global scale – by the accumulation of carbon in terrestrial and oceanic systems known as carbon sinks.
• But since humans began using fossil fuels to power industrialisation in the 1960s, carbon dioxide (CO2 ) levels in the atmosphere have risen by nearly 100 ppm (parts per million) to reach a record high of 400 ppm due to rapidly multiplying carbon sources.
• Carbon sources are places and processes that release carbon into the atmosphere (mostly in the form of carbon dioxide, particulate carbon, and methane). These include burning fossil fuels, intensive agriculture, and raising livestock, which are leading to large scale climate changes including global warming and extreme weather phenomena.

What are natural and artificial carbon sinks? 

• Natural carbon sinks can be terrestrial – soil, forests, and grasslands – or aquatic, namely, the ocean. Currently, the oceans are the largest carbon reservoirs in the world.
• Artificial carbon sinks, meanwhile, have been proposed to combat the rising levels of carbon in the atmosphere. One such idea is to convert rapidly growing urban areas into carbon sinks by using engineered timber instead of cement, steel, and other such materials. This approach aims to not only create new carbon sinks, but to also simultaneously lower carbon emissions by reducing the demand for cement, since cement manufacture currently contributes to 8% of global CO2 emissions. 
• Another idea for an artificial carbon sink is to capture CO2 directly from air or point sources (such as factories/ industrial areas) and create a concentrated stream of CO2 for use in the production of carbon neutral fuels or carbon sequestration using various methods. Carbon sequestration methods can involve injecting CO2 into the ocean or into geologic formations. 
• Mineral sequestration of CO2 is another carbon capture method that is being explored to create carbon sinks. In this, the carbon is trapped in the form of solid carbonate compounds in sandstone and basalt. Ongoing research projects are also investigating the potential of using mining waste for CO2 sequestration.

Carbon Credits 

• Carbon credits are permits that allow the owner to emit a certain amount of carbon dioxide or other greenhouse gases. One credit permits the emission of one ton of carbon dioxide or the equivalent in other greenhouse gases. 
• The carbon credit is half of a so-called cap-and-trade program. Companies that pollute are awarded credits that allow them to continue to pollute up to a certain limit, which is reduced periodically. Meanwhile, the company may sell any unneeded credits to another company that needs them. Private companies are thus doubly incentivized to reduce greenhouse emissions. First, they must spend money on extra credits if their emissions exceed the cap. Second, they can make money by reducing their emissions and selling their excess allowances.
• Proponents of the carbon credit system say that it leads to measurable, verifiable emission reductions from certified climate action projects, and that these projects reduce, remove, or avoid greenhouse gas (GHG) emissions.

Carbon Offsetting

• Carbon offset schemes allow individuals and companies to invest in environmental projects around the world in order to balance out their own carbon footprints. The projects are usually based in developing countries and most commonly are designed to reduce future emissions. This might involve rolling out clean energy technologies or purchasing and ripping up carbon credits from an emissions trading scheme. Other schemes work by soaking up CO2 directly from the air through the planting of trees. 
• Some people and organisations offset their entire carbon footprint while others aim to neutralise the impact of a specific activity, such as taking a flight. To do this, the holidaymaker or business person visits an offset website, uses the online tools to calculate the emissions of their trip, and then pays the offset company to reduce emissions elsewhere in the world by the same amount – thus making the flight “carbon neutral”.

Carbon Tax

• A carbon tax is a type of penalty that businesses must pay for excessive greenhouse gas emissions. The tax is usually levied per ton of greenhouse gas emissions emitted. 
• A carbon tax is paid by businesses and industries that produce carbon dioxide through their operations. The tax is designed to encourage such businesses to reduce their output of greenhouse gases and carbon dioxide, a colorless and odorless incombustible gas, into the atmosphere.
• The first country to implement a carbon tax was Finland, in 1990.

Geo-Engineering 

• Geoengineering is the deliberate large-scale intervention in the Earth’s natural systems to counteract climate change. There is wide range of proposed geoengineering techniques. Generally, these can be grouped into two categories:

Solar Radiation Management (SRM) or Solar Geoengineering

• SRM techniques aim to reflect a small proportion of the Sun’s energy back into space, counteracting the temperature rise caused by increased levels of greenhouse gases in the atmosphere which absorb energy and raise temperatures. Some proposed techniques include: 
  • Albedo enhancement. Increasing the reflectiveness of clouds or the land surface so that more of the Sun’s heat is reflected back into space.
  • Space reflectors. Blocking a small proportion of sunlight before it reaches the Earth.
  • Stratospheric aerosols. Introducing small, reflective particles into the upper atmosphere to reflect some sunlight before it reaches the surface of the Earth.

Greenhouse Gas Removal (GGR) or Carbon Geoengineering 

• GGR techniques aim to remove carbon dioxide or other greenhouse gases from the atmosphere, directly countering the increased greenhouse effect and ocean acidification. These techniques would have to be implemented on a global scale to have a significant impact on greenhouse gas levels in the atmosphere. Some proposed techniques include: 
  • Afforestation. Engaging in a global-scale tree planting effort.
  • Biochar. ‘Charring’ biomass and burying it so that its carbon is locked up in the soil. 
  • Bio-energy with carbon capture and sequestration. Growing biomass, burning it to create energy and capturing and sequestering the carbon dioxide created in the process. 
  • Ambient Air Capture. Building large machines that can remove carbon dioxide directly from ambient air and store it elsewhere. 
  • Ocean Fertilisation. Adding nutrients to the ocean in selected locations to increase primary production which draws down carbon dioxide from the atmosphere.
  • Enhanced Weathering. Exposing large quantities of minerals that will react with carbon dioxide in the atmosphere and storing the resulting compound in the ocean or soil.
  • Ocean Alkalinity Enhancement. Grinding up, dispersing, and dissolving rocks such as limestone, silicates, or calcium hydroxide in the ocean to increase its ability to store carbon and directly ameliorate ocean acidification.